Systems and methods herein generally relate to image processing and more particularly to uses of files that contain printer-ready or display-ready data.
One type of graphic processing file is a print-ready file commonly known as a Portable Document Format (PDF) file. PDF is a file format used to represent documents in a manner that is independent of application software, hardware, and operating systems and was created by Adobe Systems®, San Jose, Calif., USA. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display or print the document.
A form XObject is a way of grouping a number of PDF objects together. For example, every element that makes up an item in a document can be a XObject. This allows a form XObject to be defined once in a PDF file, and used several times, which is particularly useful when combining pages or parts of pages from multiple PDF documents. Form XObjects are also used in Open Prepress Interface (OPI) workflows where the low-resolution preview of an image will be stored inside a Form XObject and the OPI information will be attached to the Form XObject. OPI workflows use a network server to store images in order to reduce memory required for high-resolution document image layout.
PostScript (PS) is a computer language for creating vector graphics developed by Adobe Systems®. PS is a dynamically typed, concatenative programming language and is best known for its use as a Page Description Language (PDL) in the electronic and desktop publishing areas.
When processing a PS job to create a PDF file, Adobe Distiller® or Normalizer® translates a PS form definition into a PDF XObject through the PS operator “execform.” Because XObjects are created when execform is executed, several XObjects may be created from the same PS form even when many of the XObjects are not necessary. This occurs because execform may detect different graphic states and decide to create another XObject even when the differences in the graphic states have no influence on the XObject itself. For large Variable Data Printing (VDP) jobs, these unnecessary XObjects can have a very significant impact on the time required to create the PDF and its final size.